Friction brake assembly



3 1954 c. A. ROBERTSON 8 FRICTION BRAKE ASSEMBLY Filed July 5, 1952 v IN VEN TOR.

1 v CHARLES A. ROBERTSON BY A r TORNE rs United Stews Pate 2,695,684 1 rnrcrroN BRAKE ASSEMBLY Charles A. Robertson, San Francisco, Calif., assignor to j Tice Valley Ranch, doing business as Dollar Industries, San Francisco, Calif., a corporation of California Application July 5, 1952, Serial No. 297,214

2 Claims. (Cl. 188-136) or gear segment provided on the shoe having a curvaturedisposed eccentrically with respect to the curvature of the face of the shoe thereby defining an arcuate wedgeshaped body or portion between the shoe face and gear segment; and. a pinion rotatably journaled to the stationary member inmesh engagement with the gear segment for moving said shoe into and out of wedged frictional engagement with respect to the braking surface on the rotating member.

A particular object and advantage of the invention is to provide a friction brake assembly which incorporates a brake shoe provided with a wedge-shaped body, by which it is possible, through cooperation of associated elements, to cause the brake shoe to be tightly and firmly wedged or forced into frictional engagement with a brake drum or equivalent member presenting a braking surface. The arrangement is such that extremely eflicient and sure braking action may be effected with no practical possibility of the braking elements becoming locked or jammed so that release of the brake is rendered diflicult. Another object and advantage of a brakeassembly embodying the invention is that the efliciency and efiectiveness of the brake is not affected to any noticeable or practical extent by virtue of prolonged use thereof,

- with resultant partial wearing away and thinning of the brake lining. More specifically, the movement of the shoe against the brake drum into tightly-wedged frictional engagement is not dependent upon or affected by the thickness, per se, of the brake lining material; and, for all practical purposes, a shoe with lining which has worn fairly thin will brake as effectively as a shoe provided with new or unworn lining.

Another object and advantage of the invention is to provide a brake shoe and drum assembly which is of a self-energizing type-i. e., as soon as the braking action is commenced, continued rotation of the drum against the brake will automatically tend to increase the amount of frictional brake resistance between the shoe and rotating drum.

Other objects and advantages of the present invention will become apparent upon reading the following specification and referring to the accompanying drawing in which similar characters of reference represent corre sponding parts in each of the several views.

In the drawing:

Fig. 1 is a fragmentary perspective view of a guy winch embodying the invention with parts thereof broken away.

Fig. 2 is an end view in section of the assembly shown in Fig. 1.

Fig. 3 is a fragmentary longitudinal sectional view of the assembly shown in Fig. 1.

Fig. 4 is an end view of a modified form of brake assembly embodying the invention incorporating an external brake shoe.

Referring now more particularly to Figs. 1, 2, and 3 in the drawing, the guy winch therein shown embodying the invention comprises, generally, a stationary supporting structure, indicated generally at A, a winch and brake 2,695,684 Patented Nov. 30, 1954 ice The stationary supporting structure A is shown ascomprising, more specifically, a' pair of spaced, similarly constructed, more or less conventional triangular frame supports with aligned axle bearings 10 which support rotatably winch and brake drum axle 11.

The winch and brake drum assembly, heretofore de signed generally at B, comprises, more specifically, a hoist drum keyed to axlell and comprising a drum body 12, about which winch cable or rope 13 is wound, and a pair of spaced circular end plates comprising a conventional gear plate 14 and a brake drum supporting plate 16. End plate 16 is provided with. an annular flange 17, the interior face of which establishes a circular braking drum surface 18 against which the brake shoe is adapted to operate. i

The brake shoe assembly, heretofore designated generally at C, comprises, more specifically, a brake shoe 19 having an arcuate shoe face, comprising conventional brake lining material 21, contoured to frictionally engage interior braking surface 18 of the brake drum 17. The backside of shoe 19 is provided with an arcuate gear segment or rack 22, the curvature of which is disposed eccentrically with respect to the curvature of shoe face 21, thereby defining an arcuate wedge-shaped body of material 23 between the gear segment and the shoe face.

In the embodiment of the invention shown in Figs. 1-3 the shoe 19 is mounted loosely interiorly of the brake drum for movement against and away from wedged frictional engagement with respect to braking surface 18 of the drum.

The brake shoe actuating means, heretofore designated generally at D, is shown as comprising, more specifically,

a pinion 26 keyed to pin or axle 27, which latter element in turn is supported rotatably within a suitable bearing provided on stationary frame A. An actuating brake handle or lever 28, keyed or otherwise secured to the outer end of axle 27, may be provided as a means for rotating the axle and pinion in either direction.

Preferably a retaining washer 24 having a diameter slightly larger than pinion 26 is disposed between said pinion and its bearing. The purpose of the retaining washer is to prevent lateral displacement of brake shoe 19 outwardly from within the confines of the brake drum.

It will be further observed that the gear teeth on both the rack 22 and pinion 26 are of a rounded stub tooth variety, and wherein the gear teeth 20a and the spaces 20 between the teeth are of substantially the same shape, although the size of the spaces are a little larger than the teeth themselves to substantially wholly accommodate said teeth when the pinion and rack are in mesh, and with substantially no clearance being provided between the top of a tooth and the bottom of the space into which said tooth projects when the pinion and rack are in mesh. It has been found that this type of gear construction functions exceptionally well in a brake assembly of the character herein described. One particular advantage of the gear arrangement is that there is no noticeable tendency of the gears to stick or lock together, regardless of how tightly the brake shoe is wedged against the brake drum, and regardless of the amount of wear on the gears which may occur after prolonged use.

The operation of the device is briefly as follows: In the arrangement shown, and referring particularly to Figs. 1 and 2, the direction of cable winding is counter-clockwise and the direction of unwinding is clockwise. The brake shoe assembly is adapted primarily to brake the drum against unwinding-i. e., when the drum is rotating in a clockwise direction. If it is desired to brake the drum during unwinding thereof and when the drum is moving in a clockwise direction, as aforesaid, handle 28 is manually moved to the right or downwardly, and the pinion-rack engagement will cause shoe 19 to move clockwise and cause the wedging of the shoe between the pinion and braking surface 18 of the drum. It is believed evident that the greater the frictional resistance between the shoe and the drum, the more will be the tendency of the revolving drum to move the shoe clockwise into tighter wedged engagement between the pinion and the 3 drum surface and thereby increase the effective braking action. Moreover, because/ ot thewedg'estructureof the shoe, it is seen that wear of the lining will not materially afiect the braking efliciency'of the device. In short, if after prolonged use tlreilining shonld wear relatively thin, the shoe can still beas t ightly wedged between :the' pinion and drum as if the lining were substantially iunworniand relatively :thicke'r.

To release the' b'rake it; is only-necessary 'to" move brake handle 28upwardlyand touhe left, which, in turn, will causep'inion 2'6 -to move shoe lining fl out "of wedged engagement against th'e di uim Because the'sho'e is'loosely mounted within the drum assembly, :it Wi'l-l, of course, continue tofriotionall y d rag against "the; drum during both winding and unwinding' rotation of s aiddrum. However, it will be found-thatin devioes such ras .guy winches, the amount of continuous relatively slight frictional contact between-the drum-and s'l'lo'e does'-'not materiallyaifect'the eflicient operativeness of-itheihoist, nor'does'it, to any pronounced extenneause prematurewearing out of the brake lining.

Fig. 3 discloses a modified brake assembly embodying the inventionsand which operates on principles generally similar to the first above'"described embodiment. In Fig. 3 the brake assemblyincorporates an eXternalbrake shoe adapted to frictionally engage :an external braking surface of a rotatablemember, More specifically, the arraugementshow'n in Fig. 3 comprises a rotatable element, comprising: a' drumflflisupported irotatably by axle 41, and defining an external circular braking surface 42. External brake shoe '43 isr-forrned withankarcuate' face, comprising brake liningmaterial=44, contoured to frictionally engage'thebraking surface-42:01? drum 40. Shoe 43 is provided witht an arcuate rack or .gear segment 46, having a: curvature disposed 'eccentricallyztothe curvature of shoeface44;-and defining:a-wedge=shapedbody 47 between the gear teeth 48 and said shoe face 44. Apinion 49 in-mesh engagement'withtrack-"46 is journal'ed to a suitable stationary support 51': andeam be: rotated in either direction upon manipulation of abrakeilevenSZ, associated with said pinion for movingitheibrake"shoe .into andout of wedgedtri'eti'onalxbrake engagementwithw respect to the braking surface 42 ofCd -rum40.

In this connection movement ofrbrake lever" 52 upward 1y will cause the pinion' 4910 rotate'iand forcethe shoe into wedged enga'geme'nt betweenthe pinion and the drum and thereby-effectbraking action on thedrum. Similarly,

to release the brake, lever 52 is moved downwardly to-the right'to'causemovemen-t of the brake shoe out of tight wedged engagement between the pinion and the d rum.

Although the invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be made within the spirit of the invention and scope of the appended claims.

I claim:

1. A friction brake assembly comprising; a circular drum defining an internal circular braking surface and a brake shoe disposed loosely within said drum having an arcuate face frictionally engaging the' inner braking surface of said drum, said shoe mounted for movement in a direction relatively toward and away from the inner braking surface of said drum for establishing correspondingly greater and lesser frictional resistance against said braking surface, an arcuate' gear rack providedx-on said shoe, the curvature of said rack disposed eccentrically' with respect-to1the curvature of said shoe-facewdefining'v'an arcuate wedge-shaped body between said rack, andlsaid: shoe face, a. member supportedstationary-with respect Ito said shoe. and adrum, ,a pinion mounted r'otata'bly son said stationary member .in mesh engagement with :said' :gear rack, and meansfor rotatingisaidpinionin eitherrdirection: for moving said shoe intoandoutofi'wedgedqfrietional: Ceinga'gement with respect to -the' brak ing surfa'ee'o'f said rum.

2. A brakeiassernbly:accordingtozclaim 1 and wherein. the gear teeth' vand-spaces' between said teeth-on saidmackand said: pinion are-rounded innprofile and are shaped and .prop'ortioned 'to present substantially no clearance between attop of: a-cgear tooth. and the space I into .whi'c'lriit projects when said pinion and ,rack are rim-mesh.

-References itd s inzthe Ifilfi-GfkthiSzPEltfiIlt UNITED STATES PATENTS Number Name ZDate' 286,998 Castleretral. h. -n Oct. .523, 1 8853- l;7'43,9911 ,Stein d Jan; 14, 1930 2,031,742 Smith: et al. .J Feb. 2-5, .1986 FOREIGN PATENTS Number Country Date:

653 ;843- France Mar. 128,. i182 

